1. Field of the Invention
The invention relates to the field of heat sealing caps to containers, and in particular, to air cooled sealing heads for inductive cap sealers.
2. Discussion of the Prior Art
It is known to seal the mouths of bottles and other containers using an inductive sealing process. Inductive sealing requires an electromagnetic-field-producing apparatus and a foil-polymer seal. Typically, the apparatus has at least one coil of wire wound to produce an electromagnetic field when electric current is supplied to the coil. It is well known in the art that electromagnetic fields induce eddy currents within metal which in turn heat the metal. The seal comprises a thin layer of aluminum foil onto which is laminated a polymer layer that is molecularly compatible with the container to be sealed. When the seal is placed onto the container and the container is placed within the electromagnetic field, the foil is heated which melts the layer of polymer. Removing the seal from the electromagnetic field allows the polymer to cool and molecularly fuse with the container to create an air-tight seal.
The strength of the electromagnetic field primarily depends upon the number of turns in the wire coil(s) and the amount of current supplied to the coil(s). To produce an electromagnetic field adequate for commercial inductive sealing, typically the power supply must output power in the order of a few kilowatts, which produces a great deal of heat. Thus, the power supply must be cooled in order to function properly. Similarly, the sealing head having the induction coil must be cooled.
Many methods of cooling the power supply and sealing head are known in the art. In particular, it is known to circulate cool water through the power supply enclosure and the sealing head. Such water cooled cap sealers, however, require complicated piping configurations that increase size and cost. It is also known to vent the power supply and force air past the outside of the sealing head. However, such air cooled cap sealers sometimes provide inadequate cooling of the sealing head which degrades the operating efficiency of the cap sealer. Also, passing cooling air into the area where the containers are being sealed can disrupt the position of the seal and/or introduce contaminants into the container of the seal.